// Navigation -- Start

  normal = new Image( 150, 50 );
  highlight = new Image( 150, 50 );
  highlight_click = new Image( 150, 50 );

  function preload_img( pre_image ) {
    if ( pre_image.name == 'nav_home' ) {
      normal.src = "pictures/nav_home_n.png";
      highlight.src = "pictures/nav_home_hl.png";
      highlight_click.src = "pictures/nav_home_hl_click.png";
    }
    if ( pre_image.name == 'nav_about' ) {
      normal.src = "pictures/nav_about_n.png";
      highlight.src = "pictures/nav_about_hl.png";
      highlight_click.src = "pictures/nav_about_hl_click.png";
    }
    if ( pre_image.name == 'nav_kontakt' ) {
      normal.src = "pictures/nav_kontakt_n.png";
      highlight.src = "pictures/nav_kontakt_hl.png";
      highlight_click.src = "pictures/nav_kontakt_hl_click.png";
    }
    if ( pre_image.name == 'nav_impressum' ) {
      normal.src = "pictures/nav_impressum_n.png";
      highlight.src = "pictures/nav_impressum_hl.png";
      highlight_click.src = "pictures/nav_impressum_hl_click.png";
    }
  }
  
  
  function bildwechsel( akt_image ) {
    preload_img( akt_image );
    if ( akt_image.src == normal.src ) {
      akt_image.src = highlight.src;
    } else if ( akt_image.src == highlight.src ) {
      akt_image.src = normal.src;
    } 
  }
  
  function on_click_image( akt_image ) {
    preload_img( akt_image );
    document.nav_home.src = "pictures/nav_home_n.png";
    document.nav_about.src = "pictures/nav_about_n.png";
    document.nav_kontakt.src = "pictures/nav_kontakt_n.png";
    document.nav_impressum.src = "pictures/nav_impressum_n.png";
    
    akt_image.src = highlight_click.src;
    if ( akt_image.name == 'nav_home' ) {
      window.location.href = 'index.html';
    }
    if ( akt_image.name == 'nav_about' ) {
      window.location.href = 'about_me.html';
    }
    if ( akt_image.name == 'nav_kontakt' ) {
      window.location.href = 'kontakt.html';
    }
    if ( akt_image.name == 'nav_impressum' ) {
      window.location.href = 'impressum.html';
    }
  }

// Navigation -- Ende

// kontakt.html -- Mailversand
  function send_mail() {
    if ( document.forms['frm_mail'].elements['firma'].value == '' ) {
      alert('Bitte einen Namen angeben!');
      exit;
    }
    if ( document.forms['frm_mail'].elements['email'].value == '' ) {
      alert('Bitte eine eMail angeben!');
      exit;
    }
    if ( document.forms['frm_mail'].elements['telefon'].value == '' ) {
      alert('Bitte eine Telefonnummer angeben!');
      exit;
    }
    if ( document.forms['frm_mail'].elements['text'].value == '' ) {
      alert('Bitte Ihr Anliegen angeben!');
      exit;
    }
    document.forms['frm_mail'].submit();

  }